"While the magnitude of structural unemployment is uncertain, I read the evidence as suggesting that the bulk of the rise during the recession was cyclical, not structural in nature," Yellen said last week.

Of course, as Yellen suggests, it is quite possible that both structural and cyclical factors are feeding into the plight of the long-term unemployed.

Still, the fact that economists are unable to agree on why the labor market has been so slow to recover suggests that no policy solution will be immediately forthcoming.

Even as little progress is made, Congress and state legislators have enacted laws making it more difficult for chronically out of work individuals to collect unemployment insurance.

More than a half million of the long-term unemployed are losing their federal extended unemployment benefits in the coming months.

The federal extended benefits program has provided the jobless with up to 20 weeks of unemployment checks after they've run through their state and their federal emergency benefits, which together last up to 79 weeks.

The scaling back of benefits has long been a priority of congressional Republicans, who worry that extended benefits are creating an dependency on government help and prolonged joblessness.

Democrats argue that unemployment benefits are an effective stimulus measure, as the money is often pumped directly into the economy in the form of consumer spending.

Baker and Hassett, the economists, argue that policymakers must recognize that long-term unemployment is a crisis, and craft a bipartisan plan to expand training plans and small business financing, reduce government red tape, and explore subsidies to expand hiring.

"Every month of delay is a month in which our unemployed friends and neighbors drift further away," they said.